(i) Field of the Invention
The present invention relates to a photosensitive resin composition. More specifically, it relates to a negative type photosensitive resin composition having excellent sensitivity and resolving properties which can inhibit volume shrinkage at the time of curing, can suitably adhere to a substrate, and can form a polyimide coating film pattern having good heat resistance on the substrate by baking.
(ii) Description of the Related Art
Photosensitive polyimides which are heat-resistant photosensitive materials have been widely used as insulating films and passivation films for semiconductors. The well known. photosensitive polyimides can be prepared by mixing a polyimide precursor with a compound having a carbon-carbon double bond capable of polymerizing by light irradiation, or chemically bonding the above-mentioned compound to the above-mentioned precursor by an ester linkage. For example, they are disclosed in Japanese Patent Application Laid-open Nos. (Sho)54-145794 and (Hei)2-144539, and Japanese Patent Publication No. (Sho)55-41422. However, in all of these polyimides, it is necessary to introduce a large amount, 50% by weight or more, of-the compound having the carbon-carbon double bond into the polyimide precursor in order to practically carry out patterning, so that deterioration of resolving properties and large volume shrinkage at curing cannot be avoided. On the other hand, there has also been suggested a method in which instead of the compound having a carbon-carbon double bond, a compound for generating an acid by light irradiation is used, whereby the above-mentioned problems can be solved. For example, Japanese Patent Application Laid-open No. 3-763 discloses a method which comprises blending the compound for generating an acid by light irradiation with a polyimide having an acyloxy group, and Japanese Patent Application Laid-open No. 4-120171 discloses a method which comprises blending the above-mentioned compound with a polyamic acid derivative into which an organic group is introduced by an ester linkage, whereby the formation of a positive type pattern can be achieved. These compositions obtained by these methods have excellent sensitivity and can inhibit the volume shrinkage at the time of curing, but the adhesion of them to the substrate is so poor that they are not practical.
An object of the present invention is to provide a negative type photosensitive resin composition having excellent sensitivity and resolving properties which inhibits volume shrinkage at the time of curing, possesses good adhesion to a substrate and can be baked.
The present inventors have intensively conducted investigation with the intention of solving the above-mentioned problems of known techniques, and as a result, they have found that these problems can be solved by a composition comprising a specific polyimide precursor whose molecular terminal has been reacted with an aminosilicon compound having a hydrolytic alkoxy group bonded to a silicon atom, and a compound for generating an acid with the aid of light. In consequence, the present invention has now been completed.
(1) A photosensitive resin composition of the present invention is characterized by a compound for generating an acid by light irradiation and at least one polyimide precursor selected from the group consisting of; (a) a silicon-containing polyimide precursor obtained from A mols of a tetracarboxylic dianhydride or its derivative formed by adding 2 mols or less of a monovalent saturated alcohol to 1 mol of the tetracarboxylic dianhydride, B mol of a diamine and C mols of an aminosilicon compound represented by the formula (1)
H2Nxe2x80x94R1xe2x80x94SiR23xe2x88x92kXkxe2x80x83xe2x80x83(1)
{wherein R1 is xe2x80x94(CH2)sxe2x80x94, 
(wherein s is an integer of from 1 to 4); R2 is independently an alkyl group having 1 to 6 carbon atoms, a phenyl group or a phenyl group substituted by an alkyl group having 7 to 12 carbon atoms; X is a hydrolytic alkoxy group; and k is 1xe2x89xa6kxe2x89xa63}
in a ratio meeting the following formulae (2) and (3)                     1        ≦                  C                      A            -            B                          ≦        2.5                            (        2        )                                          0.1          ≦                      C                          B              +              C                                ≦          1                ,                            (        3        )            
(b) a silicon-containing polyamic acid ester obtained by esterifying the precursor (a) with a monovalent saturated alcohol, and (c) partially esterified silicon-containing polyamic acid ester obtained by partially esterifying the precursor (a) with the monovalent saturated alcohol.
As further preferable embodiments,
(2) the photosensitive resin composition described in the preceding paragraph (1) wherein the silicon-containing polyimide precursor (a) is a silicon-containing polyamic acid.
(3) The photosensitive resin composition described in the preceding paragraph (1) wherein the silicon-containing polyimide precursor (a) is a polyamic acid ester.
(4) The photosensitive resin composition described in the preceding paragraph (1) wherein the polyimide precursor is the silicon-containing polyamic acid ester (b).
(5) The photosensitive resin composition described in the preceding paragraph (1) wherein the silicon-containing polyimide precursor (a) is a partially esterified polyamic acid ester.
(6) The photosensitive resin composition described in the preceding paragraph (1) wherein the polyimide precursor is the partially esterified silicon-containing polyamic acid ester (c).
(7) The photosensitive resin composition described in the preceding paragraph (1) wherein the partially esterified silicon-containing polyamic acid ester (c) is the partially esterified silicon-containing polyamic acid ester (c) which is partially imidated as much as less than 40%.
(8) The photosensitive resin composition described in the preceding paragraph (1) wherein the monovalent saturated alcohol is a monovalent saturated alcohol having 1 to 7 carbon atoms.
(9) The photosensitive resin composition described in the preceding paragraph (1) wherein X of the aminosilicon compound represented by the formula (1) is an alkoxyl group having 1 to 4 carbon atoms, and R1 is a phenylene group or a trimethylene group.
(10) The photosensitive resin composition described in the preceding paragraph (1) wherein the tetracarboxylic dianhydride is represented by the formula (4) 
the diamine is represented by the formula (5)
H2Nxe2x80x94R5xe2x80x94NH2xe2x80x83xe2x80x83(5)
the main chain of the polyimide precursor comprises e mols, f mols, n mols, m mols, h mols and i mols (each of e, f, n, m, h and i is 0 or a positive integer) of constitutional units represented by the formulae (6), (7), (8), (9), (10) and (11), respectively, 
and e, f, n, m, h and i meet the equation (12)                     0        ≦                  100          xc3x97                                    m              +              h              +                              2                ⁢                i                                                    2              ⁢                              (                                  e                  +                  f                  +                  n                  +                  m                  +                  h                  +                  i                                )                                                     less than         40                            (        12        )            
(each R3 is independently a tetravalent carbocyclic aromatic group, a heterocyclic group, an alicyclic group or an aliphatic group; each R5 is independently a divalent aliphatic group having 2 or more carbon atoms, an alicyclic group, an aromatic aliphatic group, a carbon cyclic aromatic group, a heterocyclic group or a polysiloxane group; and R6 is an alkyl group having 1 to 7 carbon atoms).
(11) The photosensitive resin composition described in the preceding paragraph (1) wherein the amount of the compound for generating an acid by light irradiation is in the range of from 0.5 to 15 parts by weight based on 100 parts by weight of the polyimide precursor.
The polyimide precursor which can be used in the photosensitive resin composition of the present invention is a specific silicon-containing polyimide precursor, a silicon-containing polyamic acid, a silicon-containing polyamic acid ester or a partially esterified silicon-containing polyamic acid.
The polyimide precursor which can be used in the photosensitive resin composition of the present invention can be obtained by carrying out a reaction for forming an amide bond between molecules of a tetracarboxylic dianhydride, its derivative formed by adding a monovalent saturated alcohol to the tetracarboxylic dianhydride or a mixture thereof, a diamine and the above-mentioned aminosilicon compound at a temperature of from 0 to 100xc2x0 C., preferably from 10 to 60xc2x0 C. in a polar solvent, or alternatively, after this reaction, further carrying out esterification.
The tetracarboxylic dianhydride which can be used herein is represented by the formula (4) 
and its derivative obtained by adding 2 mols or 1 mol of a monovalent saturated alcohol to 1 mol of the tetracarboxylic dianhydride is represented by the formula (13) or (14) 
{wherein each R3 is independently a tetravalent organic group such as a tetravalent carboncyclic aromatic group, a heterocyclic group, an alicyclic group or an aliphatic group; and R4 is an alkyl group having 1 to 7 carbon atoms}.
The smaller the number of the carbon atoms of R4 is, the smaller the volume shrinkage of the polyimide precursor at baking is. Examples of the preferable R4 include a methyl group, an ethyl group, a propyl group and a butyl group.
As the diamine, a compound represented by the formula (5)
H2Nxe2x80x94R5xe2x80x94NH2xe2x80x83xe2x80x83(5)
can be used {wherein R5 is a divalent organic group having 2 or more carbon atoms such as a divalent aliphatic group, an alicyclic group, an aromatic aliphatic group, a carbon cyclic aromatic group, a heterocyclic group or a polysiloxane group}.
Moreover, as the aminosilicon compound, a compound represented by the formula (1) can be used. In order to decrease the volume shrinkage of the polyimide precursor at the time of baking, X in the formula (1) is preferably the alkoxy group having a small number of carbon atoms. Examples of the preferable X include methoxy, ethoxy, propoxy and butoxy.
As the reaction for forming the amide bond between the molecules, there can be applied an addition reaction of the tetracarboxylic dianhydride and the amine, or a known reaction in which a dehydrating agent or a condensation agent such as N,Nxe2x80x2-dicyclohexylcarbodiimide, N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline, N,Nxe2x80x2-carbonyldiimidazole and the like is allowed to act on between the amine and the derivative formed by adding the monovalent saturated alcohol to the tetracarboxylic dianhydride. At this time, a mixing ratio of the tetracarboxylic dianhydride or the derivative formed by adding the alcohol to the tetracarboxylic dianhydride, the diamine and the aminosilicon compound which are reaction components is required to meet the above-mentioned formulae (2) and (3). If the amounts of the respective components deviate from the range of the formula (2), the viscosity of the obtained silicon-containing polyimide precursor noticeably changes with time, and shelf stability is poor. If C/(C+B) in the formula (3) is less than 0.1, sufficient photosensitivity cannot be obtained, and adhesion to the substrate is also poor.
When the silicon-containing polyimide precursor has an esterifiable portion such as a carboxyl group in its molecule, this portion can be further esterified, if necessary. The esterification or the partial esterification can be achieved by reacting the portion of the carboxyl group in the polyimide precursor with a dehydrating agent such as N,Nxe2x80x2-dicyclohexylcarbodiimide, N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline and the like to convert the same into such an isoimide as shown in the following, 
and then adding a saturated alcohol having 1 to 7 carbon atoms to the isoimide. At this time, the suitably usable alcohol is methanol, ethanol, propanol or butanol. The degree of the esterification can be changed in a wide range by controlling the amount of the isoimide which depends upon the amount of the dehydrating agent.
When the carboxyl group of the silicon-containing polyimide precursor is converted into the isoimide, imidation occurs partially owing to a side reaction, but the amount of the resulting imide is limited, which does not substantially have an influence on the present invention.
The silicon-containing polyimide precursor (a) obtained by meeting the relations (2) and (3) in the composition of the present invention contains a polyamic acid, a polyamic acid ester, a partially esterified polyamic acid ester.
The main chain of the polyimide precursor which can be used in the thus obtained photosensitive resin composition of the present invention comprises e mol, f mol, n mol, m mol, h mol and i mol (wherein each of e, f, n, m, h and i is 0 or a positive integer) of constitutional units represented by the formulae (6), (7), (8), (9), (10) and (11) 
(wherein each R3 is independently a tetravalent organic group such as a tetravalent aromatic group, a heterocyclic group, an alicyclic hydrocarbon group or an aliphatic hydrocarbon group; each R5 is independently a divalent organic group having 2 or more carbon atoms such as a divalent aliphatic group, an alicyclic group, a carbon cyclic aromatic group, a heterocyclic group or a polysiloxane group; and R6 is an alkyl group having 1 to 7 carbon atoms, and may be the same as or different from above-mentioned R4), and these constitutional units meet the equation (12)                     0        ≦                  100          xc3x97                                    m              +              h              +                              2                ⁢                i                                                    2              ⁢                              (                                  e                  +                  f                  +                  n                  +                  m                  +                  h                  +                  i                                )                                                     less than         40                            (        12        )            
When f+nxe2x89xa00, the precursor has an ester chain, but 100(2f+n+m)/2(e+f+n+m+h+i) designates a content ratio (%) of an ester side chain. The closer to 100, the value of this content ratio is, the higher the content ratio of the ester side chain is, and along with the increase of the content ratio value, the change with time of viscosity is inhibited. In consequence, shelf stability is improved, and heat stability at the time of patterning is also improved, whereby sensitivity can be improved, keeping resolution good. In addition, 100(m+h+2i)/2(e+f+n+m+h+i) corresponds to an imidation ratio.
Every polyimide precursor which can be used in the photosensitive resin composition of the present invention can be converted into a silicon-containing polyimide whose main chain is constituted of a common structural unit represented by the formula 
by baking, even if the carboxyl group and the ester portion in the precursor are present in any ratios. Therefore, the ratios of the carboxyl group and the ester structure in the polyimide precursor can be selected in compliance with a particular application.
In the polyimide precursor obtained by the above-mentioned method, the aminosilicon compound of the formula (1) is introduced into its molecular terminal, and so the precursor has a hydrolytic alkoxyl group bonded to a silicon atom at the molecular terminal. Such an alkoxyl group at the molecular terminal can form a siloxane bond as in the formula 
between the molecular terminals by condensation. This condensation can be accelerated by an acid or heat, if necessary.
In addition, the logarithmic viscosity number of this polyimide is suitably in the range of from 0.1 to 5 dl/g from the viewpoint of film formation properties. Here, the logarithmic viscosity number is xcex7inh represented by the formula (V)                               η          inh                =                                            l              n                        ⁢                          η              /                              η                o                                              C                                    (        V        )            
(wherein xcex7 and xcex70 are values measured at a temperature of 30xc2x10.01xc2x0 C. in a solution and in N-methyl-2-pyrrolidone, respectively, by the use of a Ubbelohde""s viscometer; and C is a solution concentration, i.e., 0.5 g/dl).
When the thus obtained polyimide precursor is blended with the compound for generating an acid by light irradiation, the photosensitive resin composition of the present invention can be obtained.
The amount of the compound for generating an acid by light irradiation to be blended is in the range of from 0.01 to 30 parts by weight, preferably from 0.5 to 15 parts by weight with respect to 100 parts by weight of the above-mentioned polyimide precursor. If the amount of this compound is less than 0.01 part by weight, the sensitivity is low, and if it is more than 30 parts by weight, the film quality of the cured polyimide deteriorates unpreferably.
Next, reference will be made to the tetracarboxylic dianhydride (axe2x80x2), the diamine (bxe2x80x2), the aminosilicon compound (cxe2x80x2) and the polar solvent (dxe2x80x2) which are reaction components for obtaining the silicon-containing polyimide precursor in the composition of the present invention.
Typical examples of the tetracarboxylic dianhydride (axe2x80x2) are the following known compounds, but they are not restrictive. That is, they include aromatic tetracarboxylic dianhydrides such as pyromellitic dianhydride, 3,3xe2x80x2,4,4xe2x80x2-biphenyltetracarboxylic dianhydride, 2,2xe2x80x2,3,3xe2x80x2-biphenyltetracarboxylic dianhydride, 2,3,3xe2x80x2,4xe2x80x2-biphenyltetracarboxylic dianhydride, 3,3xe2x80x2,4,4xe2x80x2-benzophenonetetracarboxylic dianhydride, 2,2xe2x80x2,3,3xe2x80x2-benzophenonetetracarboxylic dianhydride, 2,3,3xe2x80x2,4xe2x80x2-benzophenonetetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl) ether dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride and the like; alicyclic tetracarboxylic dianhydrides such as cyclobutanetetracarboxylic dianhydride, methylcyclobutanetetracarboxylic dianhydride and the like; and aliphatic tetracarboxylic dianhydride such as 1,2,3,4-tetracarboxybutane dianhydride and the like.
Typical examples of the derivative obtained by adding a saturated alcohol to the tetracarboxylic dianhydride which can be used in the present invention include those which can be obtained by adding saturated alcohols having 1 to 7 carbon atoms such as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol and the like to the above-mentioned typical examples of the tetracarboxylic dianhydrides.
Typical examples of the diamine (bxe2x80x2) are the following compounds, but they are not restrictive. That is, they include aromatic diamines such as 4,4xe2x80x2-diamino diphenyl ether, 3,4xe2x80x2-diamino diphenyl ether, 4,4xe2x80x2-diaminodiphenylmethane, 4,4xe2x80x2-diaminodiphenylsulfone, 4,4xe2x80x2-diaminodiphenyl sulfide, 4,4xe2x80x2-di(metaaminophenoxy)diphenylsulfone, 4,4xe2x80x2-di(paraaminophenoxy)diphenylsulfone, orthophenylenediamine, metaphenylenediamine, paraphenylenediamine, benzidine, 3,3xe2x80x2-diaminobenzophenone, 4,4xe2x80x2-diaminobenzophenone, 4,4xe2x80x2-diaminodiphenyl-2,2-propane, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 4,4xe2x80x2-bis(4-aminophenoxy)biphenyl, 2,2-bis{4-(4-aminophenoxy)phenyl}-hexafluoropropane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 4,4xe2x80x2-diamino-3,3xe2x80x2-diethyl-5,5xe2x80x2-dimethyldiphenylmethane, 4,4xe2x80x2-diamino-3,3xe2x80x2,5,5xe2x80x2-tetramethyldiphenylmethane, 1,4-diaminotoluene, metaxylylenediamine, 2,2xe2x80x2-diamehylbenzidine and the like; aliphatic diamines such as trimethylenediamine, tetramethylenediamine, hexamethylenediamine, 2,11-dodecanediamine and the like; silicon-based diamines such as bis(paraaminophenoxy)dimethylsilane, 1,4-bis(3-aminopropyldimethylsilyl)benzene and the like; alicyclic diamines such as 1,4-diaminocyclohexane, bis (4-aminocyclohexyl)methane, isophoronediamine and the like; guanamines such as acetoguanamine, benzoguanamine and the like.
As the diamine, a diaminopolysiloxane can also be used, but its examples include compounds represented by the formulae (wherein p is in the range of from 1 to 100): 
Known diamines other than mentioned above can also be widely used.
Typical examples of the aminosilicon compound (cxe2x80x2) are the following compounds, but they are not always restrictive. That is, they include aminomethyl-di-n-propoxy-methylsilane, (xcex2-aminoethyl)-di-n-propoxy-methylsilane, (xcex2-aminoethyl)-diethoxyphenylsilane, (xcex2-aminoethyl)-tri-n-propoxysilane, (xcex2-aminoethyl)-dimethoxy-methylsilane, (xcex3-aminopropyl)-di-n-propoxy-methylsilane, (xcex3-aminopropyl)-di-n-butoxy-methylsilane, (xcex3-aminopropyl)-trimethoxysilane, (xcex3-aminopropyl)-triethoxysilane, (xcex3-aminopropyl)-di-n-pentoxy-phenylsilane, (xcex3-aminopropyl)-methoxy-n-propoxy-methylsilane, (xcex4-aminobutyl)-dimethoxy-methylsilane, (3-aminophenyl)-di-n-propoxy-methylsilane, (4-aminophenyl)-tri-n-propoxysilane, [xcex2-(4-aminophenyl)-ethyl]-diethoxy-methylsilane, [xcex2-(3-aminophenyl)-ethyl]-di-n-propoxy-methylsilane, [xcex3-(4-aminophenyl)-propyl]-di-n-propoxy-methylsilane, [xcex3-(4-aminophenoxy)-propyl]-di-n-propoxy-methylsilane, [xcex3-(3-aminophenoxy)-propyl]-di-n-butoxy-methylsilane, (xcex3-aminopropyl)-methyl-dimethoxysilane, (xcex3-aminopropyl)-methyl-diethoxysilane, (xcex3-aminopropyl)-ethyl-di-n-propoxysilane, 4-aminophenyl-trimethoxysilane, 3-aminophenyl-trimethoxysilane, 4-aminophenyl-methyl-di-methoxysilane, 3-aminophenyl-dimethyl-methoxysilane, 4-aminophenyl-triethoxysilane and the like.
Typical examples of the solvent (dxe2x80x2), in which the above-mentioned reaction components (axe2x80x2), (bxe2x80x2) and (cxe2x80x2) are reacted, include N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, tetramethyl urea, pyridine, hexamethylphosphoramide, methylformamide, N-acetyl-2-pyrrolidone, 2-methoxyethanol, 2-ethoxybutanol, 2-butoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, cyclopentanone, cresol, xcex3-butyrolactone, isophorone, N,N-diethylacetamide, N,N-diethylformamide, N,N-dimethylmethoxyacetamide, tetrahydrofuran, N-methyl-xcex5-caprolactam, tetrahydrothiophene dioxide (sulpholane) and the like.
The above-mentioned polar solvents can be diluted with another non-protonic (neutral) organic solvent, and examples of such an organic solvent include aromatic, alicyclic and aliphatic hydrocarbons and chlorinated derivatives thereof (benzene, toluene, xylene, cyclohexane, pentane, hexane, petroleum ether, methylene chloride etc.), alcohols and dioxanes.
As the compound for generating an acid by light irradiation which can be used in the composition of the present invention, many known compounds and mixtures thereof can be used. Typical examples of these compounds include onium compounds such as ammonium salts, diazonium salts, iodonium salts, sulfonium salts, selenium salts, arsonium salts and the like; organic halogen compounds such as phenyltrihalomethylsulfone compounds, halomethyltriazine compounds, halomethyloxadiazole compounds and the like; and sulfonic acid-generating agents such as esters or amide compounds of 1,2-naphthoquinonediazido-(2)-4-sulfonic acid, sulfonic acid ester compounds of nitrobenzyl alcohols, sulfonic acid ester compounds of oximes, sulfonic acid ester compounds of N-hydroxyamides or imides, xcex2-ketosulfone compounds, and sulfonic acid ester compounds of benzoin and the like.
Typical examples of the above-mentioned compounds are the following compounds the invention is not to be construed as being limited thereto. That is, they include di(paratertiarybutylbenzene) diphenyliodonium trifluoromethane sulfonate, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluorophosphate, diphenyliodonium trifluoromethane sulfonate, benzenediazoniumparatoluene sulfonate, 4-p-tryl-mercapto-2,5-diethoxy-benzenediazonium hexafluorophosphate, diphenylamine-4-diazonium sulfate, tri(tertiarybutylphenyl)sulfonium trifluoromethane sulfonate, triphenylsulfonium trifluoromethane sulfonate, triphenylselenium tetrafluoroborate, orthonitrobenzylparatoluene sulfonate, benzoin tosylate, benzoinmethane sulfonate, benzointrifluoromethane sulfonate, benzoin-2-trifluoromethanebenzene sulfonate, anisoin tosylate, anisoinmethane sulfonate, anisointrifluoromethane sulfonate, anisoin-2-trifluoromethanebenzene sulfonate, 1-benzoyl-1-methylsulfonyloxy-cyclohexane, 2-[(p-tolylsulfonyl)oxy]-1-phenyl-1-octanone, 2-[(xcex2-naphthylsulfonyl)oxy]-1-phenyl-1-propanone, 2-[(p-acetoamidophenylsulfonyl)oxy]-1-phenyl-1-propanone, benzamido tosylate, benzamidomethane sulfonate, N-tosyloxyphthalimide, N-[(2-trifluoromethanebenzenesulfonyl)oxy]phthalimide, N-tosyloxy-1,8-naphthalimide, N-[(2-trifluoromethanebenzenesulfonyl)oxy]-1,8-naphthalimide, N-tosyloxy-2,3-diphenylmaleimide, N-[(2-trifluoromethanebenzenesulfonyl)oxy]-2,3-diphenylmaleimide, 4-(di-n-propylamino)-benzonium tetrafluoroborate, 4-methyl-6-trichloromethyl-2-pyrrone, 4-(3,4,5-trimethoxystyryl)-6-trichloromethyl-2-pyrrone, 4-(4-methoxystyryl)-6-(3,3,3-trichloropropenyl)-2-pyrrone, 2-trichloromethylbenzimidazole, 2-tribromomethylquinone, 2,4-dimethyl-1-tribromoacetylbenzene, 4-dibromoacetylbenzoic acid, 1,4-bisdibromomethyl-benzene, tris-dibromomethyl-s-triazine, 2-(6-methoxy-naphthyl-2-yl)-4,6-bis-trichloromethyl-s-triazine, 2-(naphthyl-1-yl)-4,6-bis-trichloro-s-triazine, 2-(naphthyl-2-yl)-4,6-bis-trichloromethyl-s-triazine, 2-(4-ethoxynaphthyl-1-yl)-4,6-bis-trichloromethyl-s-triazine, 2-(benzopyranyl-3-yl)-4,6-bis-trichloromethyl-s-triazine, 2-(4-methoxy-antracen-1-yl)-4,6-bis-trichloromethyl-s-triazine, 2-(phenethyl-9-yl)-4,6-bis-trichloromethyl-s-triazine, 2-phenyl-5-trichloromethyloxadiazole, 2-(p-methoxyphenyl)-5-trichloromethyloxadiazole, 2-styryl-5-trichloromethyloxadiazole, 2-(n-butyl)-5-trichloromethyloxadiazole, xcex1-trifluoroacetophenoneoxime-4-hydroxybenzene sulfonate, 9-(4-hydroxybenzenesulfonyloxyimino)-fluorene, 9-(4-methacylamidomethylbezenesulfonyloxyimino)-fluorene, 2-(4-methoxystyryl)-4,6-bis-(trichloromethyl)-s-triazine, diphenyl(4-thiophenoxyphenyl)-sulfoniumhexafluoro antimonate, (4-methoxyphenyl)phenyliodonium trifluoromethane sulfonate, 2,6-dinitrobenzyl tosylate, N-[(methanesulfonyl)oxy]-2-(xcex1-naphthyl)-3-phenyl-maleimide, N-[(trifluoromethanesulfonyl)oxy]-2-(xcex1-naphthyl)-3-phenylmaleimide and the like. However, these compounds are not restrictive.
Furthermore, in the photosensitive resin composition of the present invention, a sensitizing agent, a dye, a pigment, a surface active agent and the like can be used, if necessary.
The photosensitive resin composition of the present invention is usually supplied in the state of a solution. This photosensitive resin composition is applied to a substrate, and after the removal of the solvent, the composition on the substrate is irradiated with light to generate an acid. The thus generated acid functions as a catalyst, so that condensation proceeds between the alkoxy groups of the aminosilicon compound introduced into the silicon-containing polyimide precursor (polyimide precursor). As a result, the portion which has undergone the light irradiation becomes insoluble in any of the organic solvents mentioned above as the examples of the reaction solvents or an aqueous alkaline solution, and by the utilization of this fact, a relief pattern of a negative type silicon-containing polyimide precursor (negative type polyimide precursor) can be formed. In the thus obtained patterned silicon-containing polyimide precursor (polyimide precursor) and a cured material subjected to imidation by heating and dehydration or alcohol-removal and condensation between the alkoxy groups, an aminosilicon compound which contributes to the adhesion to the substrate is introduced into the polymer, and therefore the adhesion to the substrate is excellent and a substrate treatment using a coupling agent is not required any more. In addition, since the photosensitivity can be given only by blending a small amount of the compound for generating the acid with the aid of light, the volume shrinkage at the time of curing can be inhibited.
Next, reference will be made to procedures for forming the patterned silicon-containing polyimide precursor (polyimide precursor) and the silicon-containing polyimide by the use of the photosensitive resin composition of the present invention.
The photosensitive resin composition of the present invention can be applied to a substrate such as a silicon wafer, a metal plate, a plastic plate or a glass plate by a known means such as spin coating, immersion, printing, dispensing, roll coating and the like. The resultant coating film is prebaked at a temperature of from 30 to 150xc2x0 C., preferably from 60 to 110xc2x0 C. for a period of several minutes to several of minutes by the use of a heating means such as an electric furnace, a hot plate and the like to remove most of the solvent in the coating film therefrom.
Afterward, a negative mask is put on this coating film, followed by irradiation with chemical rays. Examples of the chemical rays include X rays, electron beams, ultraviolet rays and visible light, but ultraviolet rays and electron beams are particularly desirable. In succession, if necessary, the curing due to the condensation with the acid generated by the light irradiation can be accelerated by heating the coating film at a temperature of from 30 to 200xc2x0 C., preferably from 60 to 190xc2x0 C. for a period of from 30 seconds to 15 minutes by means of the above-mentioned heating means.
Next, the unexposed portion is removed from the coating film by a developing agent to obtain a relief pattern. Examples of the developing solution used herein include the organic solvents mentioned above as the reaction solvents and mixtures of these solvents and poor solvents such as alcohols, xylene, water and the like. In addition to the above-mentioned organic solvents, there can also be used, as the developing solution, aqueous solutions of inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate and ammonia; aqueous solutions of organic amines such as ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, tetramethylammonium hydroxide, trimethylhydroxyethylammonium hydroxide and the like, and, in some cases, solutions formed by mixing these aqueous solutions with alcohols. Next, if necessary, the coating film is rinsed in a poor solvent such as an alcohol, water and the like, and then dried at a temperature of 150xc2x0 C. or less. At any point of time after the prebaking, the film is peeled from the substrate, and it can also be used as a single film.
The silicon-containing polyimide precursor (polyimide precursor) of the relief pattern formed by the development is in the form of the precursor of a polyimide, and so it is heated at a temperature of from 200 to 500xc2x0 C., preferably from 300 to 400xc2x0 C. for a period of from several minutes to several of minutes by the above-mentioned heating means, whereby the polyimide precursor is dehydrated or is removed to close a ring and to thereby perform imidation, and in the portion of the aminosilicon compound, the condensation of the alkoxy groups proceeds, so that a patterned silicon-containing polyimide film is formed.
In accordance with such a procedure, the patterned heat-resistant silicon-containing polyimide film can be obtained from the photosensitive resin composition of the present invention. The photosensitive resin composition of the present invention can be applied to electronic materials, particularly various kinds of protective films for semiconductors, flattened films, passivation films, buffer coat films, xcex1-ray shield films for LSI memories, interlayer insulating films, interlayer films of multi-layer plates of printed-wiring boards, aligned films of liquid crystals heat storage materials of thermal heads, and the like.
The photosensitive resin composition of the present invention can be easily manufactured by a method described in this specification, and a negative type sharp relief pattern can be formed from the composition. In addition, the decrease or shrinkage of a film at the time of curing by baking is small, and the adhesive properties of the film to a substrate are excellent.